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Always use 2-byte PictureID in VP8Payloader #377

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Merged
fippo merged 1 commit into from
Oct 8, 2026
+15 −26
Merged

Always use 2-byte PictureID in VP8Payloader #377

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25 changes: 7 additions & 18 deletions codecs/vp8_packet.go
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Original file line number Diff line number Diff line change
Expand Up @@ -36,14 +36,11 @@ func (p *VP8Payloader) Payload(mtu uint16, payload []byte) [][]byte { //nolint:c
* first packet of each encoded frame.
*/

// Like libwebrtc, always use the 15-bit PictureID so the descriptor size
// does not change and SFUs can rewrite the PictureID in place.
usingHeaderSize := vp8HeaderSize
if p.EnablePictureID {
switch {
case p.pictureID < 128:
usingHeaderSize = vp8HeaderSize + 2
default:
usingHeaderSize = vp8HeaderSize + 3
}
usingHeaderSize = vp8HeaderSize + 3
}

maxFragmentSize := int(mtu) - usingHeaderSize
Expand All @@ -68,18 +65,10 @@ func (p *VP8Payloader) Payload(mtu uint16, payload []byte) [][]byte { //nolint:c
first = false
}
if p.EnablePictureID {
switch usingHeaderSize {
case vp8HeaderSize:
case vp8HeaderSize + 2:
out[0] |= 0x80
out[1] |= 0x80
out[2] |= uint8(p.pictureID & 0x7F) // nolint: gosec // G115 false positive
case vp8HeaderSize + 3:
out[0] |= 0x80
out[1] |= 0x80
out[2] |= 0x80 | uint8((p.pictureID>>8)&0x7F) // nolint: gosec // G115 false positive
out[3] |= uint8(p.pictureID & 0xFF) // nolint: gosec // G115 false positive
}
out[0] |= 0x80
out[1] |= 0x80
out[2] |= 0x80 | uint8((p.pictureID>>8)&0x7F) // nolint: gosec // G115 false positive
out[3] |= uint8(p.pictureID & 0xFF) // nolint: gosec // G115 false positive
}

copy(out[usingHeaderSize:], payloadData[payloadDataIndex:payloadDataIndex+currentFragmentSize])
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16 changes: 8 additions & 8 deletions codecs/vp8_packet_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -103,27 +103,27 @@ func TestVP8Payloader_Payload(t *testing.T) {
{{0x10, 0x91}, {0x00, 0x91}},
},
},
"WithPictureID_1byte": {
"WithPictureID_small": {
payloader: VP8Payloader{
EnablePictureID: true,
pictureID: 0x20,
},
mtu: 5,
mtu: 6,
payload: [][]byte{
{0x90, 0x90, 0x90},
{0x91, 0x91},
},
expected: [][][]byte{
{
{0x90, 0x80, 0x20, 0x90, 0x90},
{0x80, 0x80, 0x20, 0x90},
{0x90, 0x80, 0x80, 0x20, 0x90, 0x90},
{0x80, 0x80, 0x80, 0x20, 0x90},
},
{
{0x90, 0x80, 0x21, 0x91, 0x91},
{0x90, 0x80, 0x80, 0x21, 0x91, 0x91},
},
},
},
"WithPictureID_2bytes": {
"WithPictureID_large": {
payloader: VP8Payloader{
EnablePictureID: true,
pictureID: 0x120,
Expand Down Expand Up @@ -159,10 +159,10 @@ func TestVP8Payloader_Payload(t *testing.T) {
{0x90, 0x80, 0xFF, 0xFF, 0x90, 0x90},
},
{
{0x90, 0x80, 0x00, 0x91, 0x91},
{0x90, 0x80, 0x80, 0x00, 0x91, 0x91},
},
{
{0x90, 0x80, 0x01, 0x92, 0x92},
{0x90, 0x80, 0x80, 0x01, 0x92, 0x92},
},
},
},
Expand Down
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